Sleep disorders are very common with millions of adults in the United States alone reported as having trouble with sleeping to such an extent that they require consultation with a physician. Two very common types of disorders are sleep apnea and periodic leg movement.
Periodic leg movement is characterized by unilateral or bilateral leg twitches that repeat every 20 to 40 seconds. Episodes may last from 5 minutes to 2 hours and alternate with periods of normal sleep. Such movements cause fragmented or unrefreshing sleep.
Sleep apnea is characterized by a cessation of breathing. Such cessation varies with different types of sleep apnea from a cessation of airflow with a lack of respiratory effort to a cessation of airflow in the presence of continued thoractic movements and exaggerated inspiratory efforts. Serious cases of sleep apnea may show over 500 apneas per night, each one lasting 10 to 120 seconds, none of which is usually remembered by the sleeping person who may be aroused by the apnea.
Medical diagnoses of these two common sleep disorders now follows a standard protocol. About one hour before bedtime, the sleeper arrives at the laboratory, fills out some questionnaires, and has electrodes and sensors applied to his body. Electrodes are applied to the scalp, eye, chin, and earlobes. These sensors remain on the body for the course of a night's sleep in order to measure airflow, respiratory effort, EKG, and surface EMG over the right and left tibias. This is a very expensive procedure and because of the expense, makes follow-up treatment difficult.